I have an '87 Vanagon, the engine runs rough, has no power up hills, smell's 
rich.  The muffler seems to get extra hot.  My right head gasket leaks water.
Compression is ok.  I've installed new plugs and they get good spark.
I suspect the oxygen sensor.  How do I check it?  Does it put out voltage, 
or should it read so many ohms? 

Thanks for your comments,
Rick Laney